Fluid pressure operated apparatus



Sept. 9, 1941. voN K. HOTT FLUID PRESSRE OPERATED APPARATUS 5 sheets-sheetl 1 Filed March 29, 1939 /1/5 A TTU/MEV Sept. 9, 1941. l. voN K. HOTT FLUID PRESSURE OPERATED APPARATUSA Filed March 29, 1939 5 Sheets-Sheet 2 Sept. 9, 1941. l. voN K. HOTT I FLUID PRESSURE OPERATED APARATUS l Filed March 29, 1939 5 Sheets-Sheet 3 /7/5 A 7mm/Fx Sept. 9,1941. 1. voN K. HOTT FLUID PRESSURE OPERATED APFARATUS Filed March 29. 1939 5 Sheets-Sheet 4 MNHN@ Sept. 9, 41941. l. voN K. HOTT FLUID PRESSURE OPERATED APPARATUS Filed March 29, 1959 5 `Sheets-Sheet 5 E. y. w. 0r E N m@ E m .m WK T 2H M, A@ N .5 y a w h I /A v ///////W/ \s\\\\\\\\\\\\\\ /J Lw/ 4 x ...mi w 4 m w v1, 7. l. .l l n Patented Sept. 9, 194i FLUID PRESSURE OPERATED APPARATUS v Ion Von Kert Hott, Dayton, Ohio, assigner to The Joyce-Cridland Company, Dayton, Ohio, a corporation of Ohio 28 Claims.

This invention relates to a fluid pressure operated apparatus and more particularly to an apparatus provided with means for recovering and utilizing air under pressure which is ordinarily wasted. In various types of air operated apparatus the air remains under pressure in a work receptacle after the work has been performed, and the present apparatus is designed to recover that air without substantial loss of pressure and return it to the compressor where it is further compressed for subsequent use. The present application is a continuation in part of my application for patent Serial No. 195,113, iiled March 10, 1938, and now abandoned, in which there is shown and described one form of aparatus for :accomplishing this result. The present apparatus is in the nature of an improvement on and further `development of the apparatus there shown.

One object of the invention is to pro-vide such .an apparatus with improved means for controlling the operation thereof.

A further object of the invention is to pro- -vide such an apparatus having means for con- A,necting the air space in the work receptacle with :the compressor substantially simultaneously With ithe interruption of the supply of air under pressure to the work receptacle.

A further object of the invention is to provide a hydro-pneumatic lift having a unitary device for .controlling the raising and lowering of the ram :and the return of the airunder pressure to the compressor.

A further object of the invention is to provide :such a lift with means whereby air under pres- ;sure may be withdrawn from the Work receptacle either prior to or during the lowering of the ram.

`Other objects of the invention may appear as :the apparatus is described in detail.

In the accompanying drawings Fig.V 1 is a front ielevation of an installation embodying the present :invention :omitting the lifting mechanism per se; Fig. Z is a front elevation of the compressor, stor- :age reservoir, work receptacle and controllingl mechanism; Fig. 3 is a side elevation of the Valves :and their controlling mechanism; Fig. 4 is a :schematic View of an installation embodying the invention; Fig. 5 is an elevation of the main valve unit; Fig. 6 is a section taken through the liquid `valve on the line -G of Fig. 5; Fig. 7 is a section taken on the line 'l-L' of Fig. 5; Fig. 8 is a section through the supply and exhaust valves taken on the line S--B of Fig. 5; Fig. 9 is a detail view of a portion of the actuating device showing one `pair of cams; Fig. l0 is a side elevation of a check valve between the compressor and the air reservoir; Fig. 11 is a section taken on the line ll-H of Fig. 10; Fig. 12 is a sectional view of the return valve unit; Fig. 13 is a section taken on the line |3-I3 of Fig. 12; Fig. 14 isa sectional view of the relief valve for the compressor; Fig. 15 is an elevation of the valve of Fig. 14; and, Fig. 16 is a rear elevation of the actuating device.

In these drawings I have illustrated one embodiment of the invention and have shovm the same as applied to a hydro-pneumatic automobile lift of a known type. It will be understood, however, that this embodiment has been chosen for the purpose of illustration and that the mechanism may take various forms and may be applied to fluid operated apparatus of various kinds.

The operation of the apparatus can best be understood by reference to the schematic view of Fig. 4. As there shown, the lift comprises a Vertical cylinder 20, preferably sunk in the ground, and a ram 42i mounted in said cylinder and provided at its upper end with a loady supporting structure, a portion of which is shown at 22. The cylinder 20 is connected by a conduit 23 with a receptacle 24 for the oil or other liquid propellant which is utilized in the operation of the lift. The liquid propellant is forced from the receptacle 24, which may be characterized as the work receptacle, by air under pressure admitted to the upper portion thereof through a supply conduit which is connected with an air compressor 25 and constitutes a discharge line therefor. This compressor may be of any suitable character and may be operated in any suitable manner, as by means of an electric motor 2li. In the arrangement here shown the supply conduit comprises a pipe 2l leading from the outlet 2B of theA compressor to a valve casing 29, a pipe 30 leading from the valve casing and connected with a pipe 3l leading to the air space in the upper portion of the Work receptacle 21E. The pipeV 2T is provided with a branch pipe 32 leading to an air storage reservoir 33 in which air under pressure is stored for 4use, Ia check valveV 3@ being interposed in the pipe 2l betweenthe branch pipe 32 and the compressor to prevent the reverse flow of air when the -compressor is not in operation; The flow of vair through the valve chamber 29, from the pipe 2l to the pipe Sil, is controlled by a sup-ply valve 35 which is preferably so arranged that it will be held to its seat by air pressure. In the present instance this Valve is provided with a stem 36 which projects beyond the wall of thecasing for engagement by an actuating device. The flow of liquid from the Work receptacle to the lift is controlled by a through the pipe 40 into the chamber 43 and close the return valve 44. Thereafter all the air passing through the valve chamber 49 Will pass to the work receptacle. When the valve 35 is closed the valve 49 is moved to a position to connect the supplemental chamber 46 and the pressure operated device 46 with the valve chamber 29 and the pressure of the air in the work receptacle will be transmitted through the pipes closed to interrupt the supply of air under presq sure to the work receptacle and the liquid valve 31 is closed to retain the ram in its elevated position.

After the supply of air to the work receptacle has been interrupted a substantial quantity of air under pressure will be retained in the air space in the upper end of theA work receptacle. In order to recover this air under pressure the Work receptacle is connected by a suitable conduit with the intake 39 of the air compresser, thereby supplying air to the Compressor under pressure and enabling such air to be again raised to working pressure by a relatively short operation of the compressor. The return conduit leading from the Work receptacle to the compressor may be of any suitable character and for the sake of simplicity of construction I have utilized the pipe 3|, which forms part of the supply conduit, as a part of the return conduit and have provided the pipe 30 with an extension 40 with which the pipe 3| communicates. The pipe 40 is connected with an inlet pipe 4| leading to the intake of the compressor and the connection between the pipe 40 and the pipe 4| is controlled by a return valve.

In the present construction this return valve forms a part of the valve unit comprising a single casing 42 having a return valve chamber 43 in which is mounted a valve 44 to control the passage of air from the pipe 4D to the pipe 4|. This valve is so arranged that it will be held in its closed position by air pressure in the pipe 4l) but it may, if desired, be provided with a spring to initially close the same. operated device is provided for opening the valve 44 and for this purpose the valve casing 42 is provided with a small cylinder, 45 into which the stem of the valve 44 extends and in which that stem is provided With a piston 46 prefer-' ably having a pressure area slightly greater than the area of the valve 44. The cylinder 45 of the pressure operated device is connected by a tube 41 with a suitable source of supply for air under pressure. Preferably the tube is connected with the supply conduit and, as here shown, it leads to a valve chamber 48 in the main valve casing 29.

The admission of air to the valve chamber 48, and therefore to the cylinder 45 of the pressure operated device, is controlled by a valve 49 which preferably has a part extending beyond the Wall of the main valve casing for engagement byan actuating device. When the valve 49 is in one position a port 59 is open to connect the valve chamber 48 with the interior of the main valve casing 29. When the valve 49 is in another position the port 59 will be closed and a relief port 5| will be opened to vent the valve chamber 48 and thereby relieve the pressure on the piston 46 of the pressureoperated device. When the supply valve 35 is opened the valve 49 will be moved to a position to vent the supplemental chamber 48, and a portion of the air which passes through the valve chamber 29will pass A fluid pressure 3| and 39 to the air in the valve casing 29 and a portion of this air will pass through the supplemental chamber 48 to the pressure operated device 4,6` and open the valve 44. That valve at this time will be subject to the pressure of the vair from the work receptacle but the piston 46 is of an area sufficiently large to open the valve, thus permitting air under pressure from the Work receptacle to W to the intake of the compressor, if the latter is in operation, and this air will be further compressed and discharged from the compressor to the reservoir 33. When the apparatus is idle the air reservoir 33 usually contains air under pressure to initiate the movement of the ram 2| but air from the reservoir is not always suiilcient to complete the movement of the lift and as the pressure in the reservoir falls the operation of the compressor will be initiated, by a pressure controlled device hereinafter described, and will thereafter deliver air directly from the compressor to the work receptacle without passing through the reservoir. When the operation of the lift has been completed and the supply of air to the Work receptacle has been interrupted the compressor will usually operate for a substantial period of time to restore the pressure in the air` reservoir 33. It is during this period of operation that it is preferred to return the air from the Work receptacle to the compressor.

When the return valve 44 is closed the intake Qf the compressor is connected with the atmosphere or other source of low pressure air and, as here shown, the-inlet pipe 4| is connected through the valve casing 42 with a short pipe 5 2 which is in open communication with the atmosphere, a check valve 53 being interposed between the pipes 4| and 52 and so arranged that it will be closed by back pressure in the pipe 4| or by return air entering that pipe from the valve chamber 43.

The air is usually returned from the work receptacle 24 to the compressor 25 while the liquid valve 31 is closed to retain the ram in its elevated position. When this valve is opened to permit the lowering of the ram the liquid will be forced from the lift cylinder 20 through the pipe 23 to the work receptacle and the air which remains in the work receptacle, at low pressure, must be permitted to escape therefrom. For this purpose the valve casing 29 is provided with a second supplemental chamber 54 which is connected with a pipe 55 leading to the atmosphere, this pipe being in the present instance connected with the pipe 52 through which atmospheric air is supplied to the compressor. The connection between the supplemen-tal chamber 54 and the interior of the valve casing 29 is controlled by a valve 56 so arranged that it will be held in its closed position by pressure in the Valve casing'and, in the present instance, having a valve stem 51 extending beyond the wall of the valve casing for engagement by an actuating device. When the liquid valve 31 is opened to lower the lift thevalve 56will also be opened, thereby permitting. air to iiow from the. Work receptacle lthrough pipes 3l and 30 to the valvechamber 29 and thence through the supplemental chamber 54 and pipe 55 to the atmosphere. This air is under Vlow pressure and if thefcompressor is in operation it will pass the check valve 53 to the f inlet pipe 4| and the compressor.

The several valves associa-ted with the valve casing 29 may be manipulated in any suitable manner to control the operation of the apparatus but I prefer to provide a unitary actuating device which will actuate the valves at the proper times and in the proper sequence. As here shown, that actuating device comprises a member 58 having movement in two directions and it is provided with cam surfaces 59 and 60 arranged to engage respectively the stem 36 of the valve 35 and the stem 51 of the valve 56. These cam surfaces are so arranged that when the member 58 is in its intermediate or neutral position both valves will be closed and the movement of the member 53 in one direction from its neutral position will open the supply valve 35 and its movement in the other direction from its neutral position will open the exhaust valve 56. 'Ihe member 58 is also provided with cam surfaces 6l and 62 so arranged with relation to the part 38 of the liquid valve that when the member 58 is in its neutral position the liquid valve will be closed but will be moved to its open position by the movement of the actuating member 58 in either direction from its neutral position. The actuating member is also provided with other cam surfaces 63 and 64 so arranged with relation to the valve 49 that when the actuating member 58 is in its neutral position the valve 49 will be in a position to connect the valve casing 29 with the supplemental chamber 48 and the pressure operated device 46. When the actuating member 58 is moved in either direction the connection between the valve casing and the supplemental chamber will be interrupted and the port l will be opened to vent the valve chamber 48. Thus it will be apparent that when the lift is to be elevated the actuating member 58 is moved in a direction which will open the supply valve 35 and will substantially simultaneously open the liquid valve 31 and actuate the valve 49 to interrupt the connection between the valve ycasing and the supplemental valve chamber 48, thus permitting the returnvalve 44 to close. When the elevation of the lift has been completed the actuating member 58 is returned to its initial position, thereby causing the supply valve 35 and the liquid valve 31 to be closed and the valve 43 to be moved to a position to open the port 50 and connect the valve casing with the pressure operated device 45, thus causing the return valve to be opened to permit air under pressure to pass from the work receptacle to the compressor, provided the compressor is operating, as will be described. When ythe lift is to be lowered the actuating member is moved in the other direction, that is, in a direction to open the exhaust valve 56 and this movement will also open the liquid valve 31 to permit the liquid -to flow from the lift cylinder to the work receptacle and will move the valve 49 to a position to interrupt the connection between the supplemental chamber 4S and the valve casing and to ventY the supplemental chamber, thereby permitting the return valve to close.

The means for 'controlling the operation of the compressor to normally maintain a predetermined pressure in the air reservoir 33 may be of any suitable character and is here shown as substantially similar to the pressure controlling mechanism of the above mentioned application. Brieily it comprises a switch lever 65 pivotally mounted at 65 and provided with a resilient contact 61a. to bridge stationary contacts 68 in the circuit of the motor 2B. This lever is provided with a laterally extending portion having a tapered nose 61 with which cooperates a tapered plunger 69 slidably mounted on a lever 1I pivotally mounted at 10. The movement of the plunger 69 in one direction about the axis 10 will cause it to be depressed against the action of a spring Ila and to pass the nose 61, the spring then 'causing the plunger to contact with the opposite face of the nose 61 and move the switch to its open position. When -the plunger is moved in the other direction, from the last mentioned position, the plunger will engage the other face of the nose 61 and move the lever in a direction to close the switch. The lever 1I which carries the plunger 59 is connected by a rod 12 with a diaphragm 13 in a closed casing 14 and a spring 15 acts on the rod 12 to hold the plunger 69 normally in a position to close the switch. The casing 14 is connected on that side of the diaphragm opposite the rod 12 with a tube 16 which leads, in the present instance, to the pipe 21 which, as above noted, is connected with the reservoir 33, thereby subjecting the diaphragm to the pressure in the reservoir and when this pressure reaches a predetermined pressure it will overcome the action of the spring 15 and move the plunger to a position to open the switch.

Means are also provided for venting the compresser after its operation has ceased so as to permit it to be subsequently started under no load and in the present instance this venting means is controlled by the pressure operated means which controls the switch so as to vent the compressor as soon as the switch is opened. For

this purpose the pipe 21 is connected by a tube '11 with one end oi a valve casing 18 (Figs. 4, 14 and l5), the other end of which is connected with the atmosphere, as by a tube 15 leading to the pipe 52 which is open to the atmosphere. `Arranged within the valve casing 18 is a valve 8l] which controls the connection between the tubes 11 and 13. 1n the arrangement shown this valve has a stem 8l which projects beyond the endV of the valve casing and is arranged to be engaged and actuated by a lever 82 pivotally mounted at 83. This lever has an inclined surface 84 with which engages one end of a lever 85 pivotally mounted between its ends and having its other end connected by a link 85 with the switch lever 65, the arrangement being such that when the switch lever moves in a direction to open the switch the lever 85 will act on the inclined surface of the lever 82 and cause the latter to open the valve 80, thereby ventingthe pipe 21 and the compressor.

It is sometimes desirable to temporarily interrupt the operation of the lift in an intermediate position and this interruption may take place before the pressure in the air reservoir 33 has fallen sufficiently to start the compressor. When the movement of the lift is interrupted the main actuating device is restored to its neutral position, thereby closing the supply valve 35 and shifting the valve 43 to connect the valve chamber 48 with the interior of the main valve casing 29. At

the time the interruption takes place the return valve 44 will be closed but the pressure in the work receptacle 24 will be transmitted through pipes 3| and 30 to the main valve casing and. through the port 50 to the valve chamber 48 and will act on the piston 46 of-.the actuating device for the return valve so as to open or partly open the return valve,` thereby permittingl air under pressure in thework receptacle to escape and be wasted. To prevent this I have provided the apparatus with means for preventing the opening of the return valve when the compressor is not in operation. When the compressor is in operation the discharge pipe 21 and the vent pipe 11 contain air under high pressure but when the compressor is idle the vent valve 80 is open and there is no substantial pressure in either the pipe 21 Yor the pipe 11. I have therefore interposed in` the tube 41,` which supplies air to the pressure operated kdevice;for

the return valve, a cut-01T valve which is normally y chamber 48 but I prefer to provide a spring |50 to insure the proper and prompt closing of the valve. The casing |41 is also. provided with a cylinder |5| which is connected by a tube |52 with the vent pipe.11. Mounted in `the cylinder |5| is a piston |53 which is connected with the valve member |49 Yand will be subjected to the pressure in the vent pipe 11 to actuate the piston and open the valve member |149. The piston is of such size that the pressure in the vent tube 11, when the compressor is in operation, will overcome the pressureof both the air. and the spring on the valve member |49. Thus it will be apparent that if the movement of the lift is interrupted and the main actuating device returned to neutral position while the compressor is idle there will be no substantial pressure on the piston |53 and the supply of air to the pressure operated device for the return valve will be cut olf but as soon as the compressor comes into operation pressure will bebuilt up in the vent pipe 11 and the piston |53 actuated to open the cut-off valve and establish communication between the pressure operated device for the return valve and the valve chamber 48, thus placing said pressure operated device under the control of the valve 49 and enabling the return Valve to be opened whenever the main actuating device is returned to its neutral position while the compressor is in operation.

The general arrangement of the apparatus is illustrated in Figs. 1 and 2 where the air reservoir 33 is shown as an upright cylindrical tank and the liquid or work receptacle 24 is shown as a cylindrical tank mounted alongside of the air reservoir and of a height substantially less than the height of the air reservoir. Preferably the two tanks are connected one to the other so as to constitute a unitary structure. The compressor 25 is mounted on the top of the work receptacle and is driven by a belt 81 from the motor 26 which is mounted on a bracket 88 rigidly secured to the upper portion of the air reservoir. If desired, the reservoir may be provided with a pressure gage89. The main valve assembly including the valve casingv 29and the liquid valve, is mounted on thetop of `the work receptacle and the liquid pipe 23 extends downwardlytherefrom and:` usuallyy extends under-l ground to the lift cylinder. Preferably the mechanism which 'is mounted on the work receptacle is normally-enclosed in a removable housing 90, withV the exception of the main valve unit and :1 its actuating device which are arranged exteriorly of the housing atrthe front of the apparatus with the actuating device conveniently located for operation.

Referringnow to the specic construction of -the various parts of the apparatus the preferred arrangement of the main valve unit is shown in Figs. 5 to 9 where the main valve casing 29 is illustrated as arranged in a horizontal position. The inlet valve 35 is mounted in a supplemental valve chamber 9| formed within the main casing 29 and the stem 36 -of the Valve 35 projects forwardly beyond the valve casing. Preferably a spring 92 is provided to insure the prompt seating of the valve when it is released by the actuating device. The supplemental chamber 54 for the exhaust valve 56 is arranged at the opposite end of the valve casing 29 and the exhaust valve 56 is mounted in the main chamber of the valve casing 29 and its stem 51 extends forwardly through the chamber 54 and beyond the front wall of the valve casing. This valve is also provided with a spring 92a`to insure the prompt seating of the valve when the valve is released. The liquid valve 31 is mounted in a casing 93 inserted in and forming a part of the liquid conduit 23 and this casing 93 is, in the present instance, formed integral with the valve casing 29 and is arranged above the latter with the stem 38 of the valve 31 projecting forwardly from the front wall of the valve casing in a vertical plane arranged between the vertical planes of the stems 36 and 51 of the Valves 35 and 56. In the present instance, the valve 31 is shown as a gate valve comprising two disk-like members 94 and 95 cooperating respectively with Valve seats 96 and 91. These two members are connected one to the other by a ball and socket joint to enable the same to adjust themselves to the respective valve seats, the valve member 94 having a hub portion g. 98 provided with a socket 99 vand the Valve member having a semi-spherical projection |00 eX- tending into the socket 99. The valve stem 38 is provided with an annular portion |0| into which the hub 98 of the Valve member 94 extends, thus `.providing a pivotal support for the valve as a whole. The valve stem 38a1so has a guide portion |02 extending beyond the valve members into a closed guideway |93 and a spring |04 acts on the valve to hold the same normally in its closed position.

The actuating device 58 is here shown in the form of a metal plate or disk (see Fig. 16) having a hub portion |65 mounted for rocking movement on a stud |06 rigidly mounted in the front .wall of the valve casing 29 and, in the present instance, arranged between and substantially in the horizontal plane of the valve stems 36 and 5.1,' see Figs. 2 and 5. The cam surfaces 59 and 69,. for actuating the supply valve 35 and exhaust valve 56, are formed just above and on opposite sides of the axis ofthe actuating member. The

cam surfaces 9| and 62 for the liquid valve 31 are Y arranged above the cam surfaces 59 and 6D. The several cam surfaces are so arranged that when lthe actuating member is in its central or neutral position the sev-eral valves will be released and will be retained in their closed positions. When the actuating member is moved in one direction,

counterclockwise'in Fig..16,'the cam surface 6|! Willfengage thevalve stem.36fandopen thesup ply valve 35 and the cam 6| will engage the valve stem 38 and open the liquid valve 31. When the actuating member is restored to its initial position both valves will be released and will be automatically closed. The actuating member is provided with a handle |01 by means of which it may be manipulated and it may be restored to its neutral position either by manipulating thehandle or by releasing the same and permitting it to be returned to neutral position bythe action of the spring pressed valve stems on the cam surfaces. the opposite direction from its neutral position, that is, clockwise in Fig. 16, the cam surface 59 will engage the valve stem 51 and open the Valve 56 and the cam surface 62 will engage the valve stem 38 and open the liquid valve 31.

The supplemental valve chamber 48 for the valve 49 which controls the supply of air to the actuating device of the return valve, is formed in'. the front wall of the valve casing 29 and, in the present instance, is located just below the' stud |36 on which the actuating device is mounted. The port 5|) connects the chamber 43V with the main chamber of the valve casing 29 and the'.

port 5| connects the chamber 43 with the atmosphere. The valve 49 comprises two parts, a needle valve |08 to control the ow of air through the port 50 and a larger valve portion |33 to control the ow of air through the port 5I. The valve is held normally in its open position by a spring I I I), thus normally connecting the interior of the valve casing 29 with the pressure operated device which actuates the return valve. The

stem I I of the Valve 48 extends beyond thefront wall of the valve casing 29 and into a recess in the inner end of the hub |55 of theactuating device, the walls of this recess convergingto form the cam surfaces 63 and 64 and both valve surfaces being out of engagement with the valve stem III when the actuating device is in its'neutral position. Thus when the actuating device is moved in either direction from its neutral position the portion IBB of the valve 49 will 'close the port 5G to interrupt the supply of air to thepressure operated device, and the portion IIJ9'will open the port 5I to vent the tube 41 and the pressure operated device. When the actuating device is returned to its neutral position the Valve 49 will be automatically moved to its normal i'.

position by the spring I ||J.

The return Valve unit, as shownin Figs. 12 and 13, comprises a Valve casing 42 having a chamber 43 connected by the pipe 49 with the work receptacle and also having a chamber H22".

which is connected by the pipe '4| with the intake of the compressor. The two chambers are separated by a partition provided with a port I I3 which is controlled by a valve 44. The cylinder of the uid pressure operated device which actu? ates the valve 44 is formed in a plug r| I4 screw threaded into an opening in the casing 42 in line with the port 43, and the piston 43 which is mounted in this cylinder is connected -with the valve 44. In the present instance the piston is. D

formed separately from the valveand is operatively connected therewith by contact of the piston with the collar ||5 on the stem of the valve. The chamber ||2 is provided with a `port ||3 leading to a chamber I I1 which is connected by the pipe 52 with the atmosphere and is connected by the pipe 55 with the exhaust chamber 54 of the valve casing 29. The port H6 is controlled by the valve 53 which, in the arrangement here shown, is held in its open position by gravity.

The stem ||9 of the valve 53 extends through a `guideway |20 into a small chamber |2I formed in When the actuating member is moved in lvibration of the movable valve member.

a plug |22 screw threaded into the lower portion of the valve casing 42.v This chamber I2I is connected with a chamber I|2 by a series of ports |23 so Vthat air under pressure entering the chamber ||2 willpass through the ports |23 into the chamber I2I and act on the lower end of the valve stem to close the valve.

The check valve 34 is interposed in the pipe 21 between the air reservoir 33 andthe compressor and is preferably of the construction shown in l'l'igs. 10 and 11, and, as there shown, is of such a type as to prevent chattering or The valve casing comprises an outlet chamber |24 which is connected with the pipe 32 leading from the air reservoir, and with an inlet chamber |25 which is connected with that portion of the pipe 21 leading to the air compressor. The chambers |25 and |24 are connected by a port |26 provided with a valve seat |21. Arranged about and extending upwardly from the port |25 is a cylinder |28 which is held in tight engagement with the valve seat about the port by a cap I 29 threaded into the upper part of the valve casing, and having a circumferential series of ports |30'near the lower end thereof. Mounted within the cylinder |28 is a piston like valve member I 3| Yarranged to move by gravity to a position to close the port |25 and to be opened by air pressure in the chamber |25 so as to permit the air to pass through the ports |26 and |35 to the chamber |24 in the normal operation of the apparatus. The piston valve lits losely in the cylinder and in the event of back pressure in the pipe 32 the air entering the chamber 24 willpass through the portsV |33 and between the piston and the cylinder to the upper end of the cylinder where it will act on the piston to close the port |25. In the arrangement here shown the cylinder |28 is provided at each end with a series of ports |33 but the I, Ll5

upper series of ports is inoperative and is provided' merely to insure that in assembling the device the cylinder will be properly inserted in the valve casing.

Associated with the check valve 34 is a relief valve to vent the air reservoir in the event of excessive pressure therein. As shown it comprises a cylindrical valve chamber I32Hformed in a lateral extension of the valve casing 34 and connected at its lower end with the valve chamber |24 by a port |33 and connected with the atmosphere by a port |34. Mounted within the chamber |32 is a piston like valve member |35V which normally engages a valve seat |35 surrounding the port |33 to close that port. The valve is held normally in its closed position by 'a spring I 31 coiled about a valve stem |38. In the present instance the valve stem |38 is separate from the valve member |35 and is provided at its lower end with a rounded head |39 which is seated in a tapered recess |43 in the valve member to permit the valve member to adjustr itself with relation to its valve seat, and the spring |31 is confined between the head |39 and the top wall of the chamber |32. The spring |31 is of suiicient strength to hold the valve in its closed position under normal operating pressure in the valve be moved against the action of the spring |31 to' connect the chamber |24 with the atmosphere through the ports |33 vand |34. The motor switch, its pressure controlled actuating mechanism and the relief' valve 18; are mounted in a casing |4| supported on the upper end portion of the air reservoir -33.

The air which is stored under pressure in' the reservoir 33 may be used not only for operating the lift but forl various other' purposes, such as operating a lubricating device, nflating tires and the like. The air reservoir is provided in its upper end with a valve controlled outlet |42 with which is connected a flexible hose lIll?. provided at its free end with a connector |44 whereby it may be attached to various iiuid pressure operated devices. The organization of the present apparatus is such-as to lend itself admirably to these other uses of the air. The assembly of the air reservoir and `the work receptacle are such that they can be arrangedl at one side of a room, preferably against a wall, adjacent to `the lift with which the apparatus is connected,vand portable fluid operated devicesY arranged at the respective sides of `the apparatus'are sho-wn at |45 in Fig. 1. Thesedevices are provided with nipples |46 to receiveV the connector |44 andv thus connect the same with the air reservoir. Thus the apparatus and itsassociated portable devices can be arranged in an orderlyvmanner which not only `facilitates their use but makes an attractive display of the various apparatus employed in the yservice station.

While I have shown and described one embodiment of my invention I wish it tobe understood that I do not desire tobe limited to the details thereof as various modiiications may occur -to a person skilled in the art.

Having now fully described my invention,what I claim as new and desire to secure by Letters Patent is:

1. In an apparatus for utilizing the-pressure energy of air to perform work includingva-*work receptacle in which air is' retained under pressure-after work has beenperforrned, an air compressor, a valve casing, conduits to connect said valve'casing with said compressor and said work receptacle, a supply valve in said casing to control the flow of air thereto from said compressor, a return conduit for connecting said work receptacle withV the intake of said compressor, a return valve inV said return conduit arranged to be held closed by pressure in said return conduit, a fluid pressure operated device to `open said return valve, means for connecting said, pressure z turn conduit to connect the air space in said receptacle with the intake of said compressor, a valve to control the passage of air through said return conduit, iiuid pressure operated means for actuating said return valve, means for connecting said pressure operated device with a source of supply of air under pressure, a valve for controlling said connection, means including an actuating device for opening said supply and liquid valves and closing the last mentioned valve when one movement is imparted to said actuating device, and for closing said supply and liquid valves, retaining the same closed to prevent the lowering oisaid lift and opening said last mentioned valve When another movement is imparted to said actuating device, and means for supplying air to said compressor While said return valve is closed.

3. In an apparatus comprising a hydraulic Y lift, a receptacle for liquid having an air space operated device with said casing between said l supply valve and the conduit leading to said work receptacle and including a valve to control said connection, means including an actuating device to open said supply valve and close'said controlling valve when saidA actuating device is moved in one directionand to close saidsupply valve and open said controlling valve to transmit the pressure from said Workreceptacle to said pressure operated device When said actuating device is moved inV another direction, and means -for supplying air to the intake of said compressor when said return valve is closed.

2. In an apparatus comprising a hydraulic lift, a receptacle for liquid having anair space above the liquid therein, a conduit `for liquid leading from saidk receptacle to said lift, a valve to control the passage of liquid through said conduit, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle,a valve to control the passage of air through said supply conduit, a reabove the liquid therein, a conduit for liquid leading from said receptacle to said lift, a normally closed valve to control the flow of liquid through said conduit, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle, a normally closed valve to control the ow of air through said supply conduit, a return conduit to connect the air space in said receptacle with the intake of said compressor, a valveto control the flow 0f air through said return conduit, fluid pressure operated means for actuating said return valve, an actuating device movable in one direction from a neutral position vto open said supply and liquid valves and movable in another direction from said neutral position to open said liquid valvel While said supply valve is closed, and means controlled by said actuating device to connect said pressure operated means with a source of supply for air under pressure for opening said return valve when said actuating device is in said neutral position and to interrupt said connection when said actuating device is moved in either direction from said 'neutral position, and means for supplying air to said compressor when said return valve is closed. 4. In an apparatus including a Vhydraulic lift,

.aliquid receptacle having an air space above the liquid` therein, a liquid conduit to connect said receptacle with-said lift, a valve to control the ow of liquid through said conduit, an air compressor, means including a valve to supply air under pressure from said compressor to said receptacle, a conduit for returning air under pressure from said receptacle to the intake of said compressor, a return valve in said return conduit, an actuating device, means controlled by said actuating device for closing said air supply valve, closing said liquid valve to retain said lift in an elevated position and opening said return valve to return air under pressure from said receptacle to said compressor while said lift is retained in said elevated position, and means for supplying air to said compressor while said return valve is closed. i

5. In an apparatus including a hydraulic lift, a liquid receptacle having an air space above the liquid'therein, a liquid conduit to connect said receptacle with said lift, a valve to control the `flow of liquid through said conduit, an air compressor, means including a valve to supply air under pressure from said compressor to said receptacle, a conduit for returning air under pres- .sure from said receptacle to the intake of said compressor, a return valve in said return conduit, an actuating device, means controlled by the successive Ymovements of said actuating device for for opening said liquid valve to lower said lift,

and means for supplying air to said compressor While said return valve is so closed.

6. In an apparatus including a hydraulic lift, a liquid receptacle having an air space above the liquid therein, a liquid conduit to connect said receptacle with said lift, a valve to control the flow of liquid through said conduit, an air compressor, means including a valve to supply air under pressure from said compressor to said receptacle, a conduit for returning air under pressure from said receptacle to the intake of said compressor, a return valve in said return conduit, an actuating device, means controlled by said actuating device for closing said air supply valve, closing said liquid valve to retain said lift in an elevated position and opening said return valve to return air under pressure from said .receptacle to said compressor While said lift is retained in Y said elevated position, means controlled by said actuating device to exhaust air from said receptacle while said return valve is closed, and means for supplying air to saidcompressor while said return valve is closed. Y

7. In a fluid operated apparatus, a closed liquid receptacle having an air space above the liquid therein, means for conducting liquid under pressure from said receptacle to a device to be operated, an air compressor, means for supplying air under pressure from said compressor to the air space in said receptacle, a return conduit to deliver air under pressure from said receptacle to the intake of said compressor, a return valve to control the flow of air through said return conduit, means including an actuating device for interrupting the supply of air from said compressor to said receptacle and for opening said return valve, means separate from said return valve and controlled by said actuating device for exhausting air from said receptacle While the supply of air thereto is interrupted, and means for supplying air to the intake of said compressor While said return valve is closed.

8. In a iiuid operated apparatus, a closed liquid receptacle having an air space above the liquid therein, means for conducting liquid under pressure from said receptacle to la device to be operated, an air compressor, means including a valve for supplying air under pressure from said oompressor to said receptacle, a conduit for returning air under pressure from said receptacle to the intake of said compressor, a return valve to control the flow of air through said return conduit, means including a valve to exhaust air from said receptacle independently of said return valve, anactuating device having means operable upon successive movements thereof to first open said supply valve and close said return valve, to then close said supply valve and open said return valve and to thereafter open said exhaust Valve, and means for supplying air to said compressor While said return valve is closed.

9. In a fluid operated apparatus, a hydraulic lift, a closed liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said receptacle With said lift, a valve to control the flow of liquid through said conduit,

an air compressor, means including a valve for 'supplying air under pressure from said compressor to said receptacle, a conduit for returning air under pressure from said receptacle to the intake of said compressor, a return valve to control the iloW of air through said return conduit, means other than said returny conduit and including a valve to exhaust air from said receptacle, an actuating device having means operable Vupon successive movements thereof to first open said supply and liquid valves and close said return valve, to then close said supply and liquid valves and open said return valve and to thereafter open said liquid and exhaust valves, and means for supplying air to said compressor While saidreturn valve is closed.

l0. In a fluid operated apparatus,V a hydraulic lift, a closed liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said receptacle With said lift, a valve to control the flow of liquid through said conduit, an air compressor, means including a valve for supplying air under pressure from said compressor to said receptacle, a conduit for returning air under pressure from said receptacle to the intake of said compressor,'a return valve to control the flow of airthrough said return conduit, a iluid operated device to open said return valve, means including a control valve to connect said iluid operated device with said air supply means, means including an exhaust valve for exhausting air'from said receptacle independently of said return valve, an actuating device having means operable on successive movements thereof to iirst open said supply and liquid valves and close said control valve, to then close said supply and liquid valves and open said control valve and to thereafterv open said exhaust and liquid valves, and means to supply air to said compressor While said return valve is closed.

1l. In an apparatus comprising a hydraulic lift, a receptacle for liquid having an airspace above the liquid therein, a conduit for liquid leading from said receptacle to said lift, a valve to control the passage of liquidlthrough sai-d conduit, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle, a valve to control the passage 'of air through said supply conduit, a return conduit to connect the air space in said receptacle with the intake of said compressor, a valve to control the passage of air through said return conduit, fluid pressure operated means for opening said return valve, means including a valve for connecting said pressure operated means with a source of supply of air under pressure, means for venting said liquid receptacle while said return valve is closed, an actuating devi-ce having means for opening said liquid and supply valves and for closing said connecting valve when moved in one direction from its normal position, and for opening said liquid valve, actuating said venting means and closing said connecting valve when moved in another direction from its normal position, and means for supplying air to said compressor While said return valve is closed.

l2. In an apparatus comprising a hydraulic lift, a receptacle for liquid having an air space above the liquid therein, a conduit for liquid leading from said receptacle to ysaid lift, a valve to control the passage of liquid through said conduit, an air compressor, a conduit to supply air under pressure from said lcompressor to the air space in said receptacle, a valve to control the passage of air through said-supply conduit, a

.return conduit to connect the air spacek in said receptacle with the intake of said compressor, a valve to control the passage of air through said return conduit, means including an exhaust valve to vent said work receptacle, a single actuating-device having' means for controlling the positions of said supply valve, said exhaust valve, saidliquid valve and said return valve.

13. In an apparatus comprising a hydraulic lift, a receptacle for liquid having an air space above the liquid therein, a conduit for liquid leading from said receptacle to said lift, a valve to control the passage of liquid through said conduit, an air compressor, a -conduit to supply air under pressure from said compressor to the air `space in said receptacle, a valve to control the passage of -air through said supply conduit, a return conduit to connect the air space in said receptacle with the intake of said compressor, a valve to -control the passage of air through said return conduit, uid pressure operated means for actuating said return Valve, means for connecting-said pressure operated device with a sour-ce of supply of air under pressure, a valve for controlling said connection, means including a valve for exhausting air from said receptacle, means including an actuating device movable in two directions from a neutral position for open- -ing said supply valve and said liquid valve and for closing the controlling valve for said pressure operated 'device when said actuating device is movedY in one direction from said neutral position, for closing said supply and liquid valves, and opening said control valve when said actuating device-is returned to its neutral position, and for openingl said exhaust valve and said liquid valve when said actuating Idevice is moved in the other direction from its neutral position, and means for supplying air to said compressor While said return valve is closed.

14.*In an apparatus comprising a hydraulic lift, a receptacle for liquid, an air compressor, means including a normally closed valve for supplying air from said compressor to said liquid receptacle, means including a normally closed valve for delivering liquid from said receptacle to said lift, means including a return valve for connecting the air space of said receptacle with .the intake of said compressor, means including a normally closed valve for exhausting air from vsaid receptacle while said return valve is closed, iiuid pressure operated means for actuating said return valve, a normally open valve to connect said fluid pressure operated means with a source of air supply, an actuating -d-evice movable in either of two dire-ctions from a neutral position and having means for opening said supply valve and said liquid valve and for closing said controlling valve when `said actuating vdevice is moved in one direction from said neutral position, and for Yopening said exhaust valve and said liquid valvewhen said actuating'device is moved in another direction from said neutral position, and .means for supplying air to said compressor while said return valve is closed.

15. In an apparatus of the character described, a work receptacle, anair compressor, means for supplying air under` pressure. from said compressor to said work receptacle including a valve casing 'and pipes connecting said valve casing lwith'said'cornpressor and with said work receptacle, a supply valve in said valve casing, an eX- haust pipe connected with said valve casing, an exhaust valvein said valve casing, a return conduit connectingffsaid work receptacle with the intake of said compressor, pressure operated means for controlling ,the flow of air through said return conduit, means including a valve in said valve casing for connecting said pressure operated means With the air supply portion of said valve casing, and a single' actuating device having. means for controlling the position of each of the three valves in said valve casing.

16. In an apparatus for utilizing the pressure energy of air to perform Work, including a work receptacle in whichy air is retained under pressure after work has been performed, an air ccmpressor, and means including-a valve for supplying air under Ipressure from said compressor to said work receptacle; a return -conduit forv connecting said Work receptacle with the intake of said compressor, a valve in said return conduit, means for actuating said return valve, means controlled byksaid compressor to prevent the opening-of said return Valve when said compres- `sor is not operating, means for actuating said supply valve, and meansfor supplying air to said compressor while said return valvev is closed.

17. In an apparatus for utilizing the'pressure energy of air to perform work, including a work receptacle in which air is retained under pressure after workhas' been performed, an air compressor, and means including a valve for supplymg air under pressurejfrom said compressor to said work receptacleya return conduit for connecting said work receptaclewith the intake of said compressor, a valve in said return conduit, a uid pressure operated device for actuating said return valve, means for connecting said pressure operated device with a source of air under pressure. means controlled by said compressor to interrupt the connection between said pressure operated device; and said air source when said compressor is idle, means for actuating said supply valve, and means for supplying air to said compressor while said return valve is closed.

18., In an apparatus for utilizing the pressure energy of air to perform work, including a work receptacle in which airis retained under pressure after workhas been performed, an air. compressor, and means including avvalve for supplying air under pressure from said compressor to said work receptacle; a return conduit for connecting said work receptacle with. the intake of said compressor, a valve in said return conduit, a fluid pressure operated device for actuating said return valve, means for connecting said pressure operated Adevice With a source of air under pressure and including a valve to control said connection, an actuating device having means to control the operation of said supply valve and said controlling valve, a cut-off valve interposed between said pressure operated device and said controlling valve, means controlled by said compressor for actuating said cut-off valve, and means for supplying air to said compressor while said return valve is closed.

i9. In an apparatus for utilizing. the pressure energy of air to perform work, including a Work receptacle in which air is retained under pressure after work has been performed, an air compressor, and means including a valve for supplying air under pressure from said compressor to said work receptacle; a return conduit for connecting said Work receptacle with the vintake of said compressor, a Vvalve in said return conduit, Aa fluid pressure operated device for actuating said: return valve, means` for connecting said .pressure operated device with a source of air under pressure, a normally closed cut-oil valve interposedv between said pressure operated device and said air source, pressure operated means for opening said cut-olf valve, means for connecting the last mentioned pressure operated means with the outlet of said compressor to cause said out-oir valve to be opened when said compressor is in operation, means for actuating said supply valve, and means for supplying air to said compressor while said return valve is closed. Y

` 20. In an apparatus including a hydraulic lift, a liquid receptacle having an air space above the liquid therein, an air compressor, means for supplying air under pressure from said compressor to said receptacle, means for connecting said receptacle with said lift to deliver liquid under pressure from said receptacle to said lift to elevate the latter and for interrupting said connection to hold said lift against downward movement, means for returning air under pressure from said receptacle to the intake of said compressor while said lift is held against downward movement, and means for supplying air to said compressor while said return means is inoperative.

21. In an apparatus including a hydraulic lift,

a liquid receptacle having an air space above the liquid therein, an air compressor, means for supplying air under pressure from said compressor to said receptacle, means for connecting said receptacle with said lift to deliver liquid under pressure from said receptacle to said lift to elevate the latter and for interrupting said connection to hold said lift against downward movement, a conduit for returning air under pressure from said receptacle to the intake of said compressor, a valve in said conduit arranged to be held closed by the pressure of air in said receptacle, a iiuid operated device to open said valve, means for supplying air under pressure to said pressure operated device to open said valve and return air under pressure from said receptacle to said compressor while said lift is held against downward movement, and means for supplying air to said compressor while said Valve is closed.

22. In an apparatus including a hydraulic lift, a liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said receptacle with said liit, a valve in said conduit, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle and thus deliver liquid under pressure to said lift, a supply valve to control the flow of air through said supply conduit, a return conduit leading from the air space in said receptacle to the intake of said compressor, a return valve in said return conduit arranged to be held in its closed position when saidsupply valve is open, means including a valve to exhaust air from said receptacle while said lift is being lowered and said return valve is closed, and means for supplying air to said compressor while said return valve is closed.

23. In an apparatus including a hydraulic lift, a liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said receptacle with said lift, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle and thus deliver liquid under pressure to said lift, a supply valve to control the ow of air through said supply conduit, a return conduit leading from the air space in said receptacle to the intake of said compressor, a return valve in said return conduit arranged to be held in its closed position when said supply valve is open, means including a valve to exhaust air from said receptacle while said lift is being lowered and said return valve is closed, a valve in said liquid conduit, means for opening said returnvalve While said liquid `Valve is closed to retain said `lift in an elevated position, and means for supplying air to said compressor while said return valve is closed.

24. In a fluid operated lifting mechanism, a hydraulic lift, a liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said receptacle with said lift, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle and thus deliver liquid under pressure to said lift, a supply Valve to control the flow of air throughV said supply conduit, a return conduit leading from the air space in said receptacle to theintake of said compressor, a return valve in said return conduit arranged to be held in its closed position when saidsupply valve is open, a liquid valve to prevent the return of liquid from said lift to said receptacle, means for opening said return valve while said supply and liquid valves are closed to permit air under pressure to flow from said receptacle to said compressor, and means for supplying air to said compressor while said return valve is closed.

25. In a fluid operated lifting mechanism, a hydraulic lift, a liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said. receptacle with said lift, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle and thus deliver liquid underpressure to said lift, a supply valve to control the flow of air through said supply conduit, a return conduit leading from the air space in said receptacle to the intake of said compressor, a return valve in said return conduit arranged to be held in its closed position when said supply valve is open, a liquid valve to prevent the return of liquid from said lift to said receptacle, means for opening said return valve while said supply and liquid valves are closed to permit air under pressure to flow from said receptacle to said compressor, and means for exhausting air from said receptacle while said supply valve is closed and said liquid valve is open to permit said liquid to now from said lift to said receptacle.

26. In a fluid operated lifting mechanism, a hydraulic lift, a liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said receptacle with said lift, an air compressor, a conduit to supply air under pressure from said compressor to the air space in said receptacle and thus deliver liquid under pressure to said lift, a supply valve to control the flow of air through said supply conduit, a return conduit leading from the air space in said receptacle to the intake of said compressor, a return valve in said return conduit arranged to be held in its closed position when said supply valve is open, a uid pressure operated device to open said return valve, a liquid valve to prevent the return of liquid from said lift to said receptacle, and means for supplying air under pressure to said pressure operated device while said supply and liquid valves are closed to open said return valve and permit air under pressure to flow from said receptacle to said compressor,

and means for supplying air to said compressor while said return valve is closed.

27. In a fluid operated lifting mechanism, a hydraulic lift, a liquid receptacle having anair space above the liquid therein, a liquid conduit connecting said receptacle with said lift, an air compressor, a conduit tosupply air under pressure from said compressor to the air space in said receptacle and thus deliver liquid under pressure to said lift, a supply valve to control the ow of air through said supply conduit, a returnconduit leading from the air space in said receptacle to the intakev of said compressor, a return Valve in said return conduit arranged to be held in its closed position when said supply valvel is open, a fluid pressure operated device to' open said return valve, a liquid Valve to prevent the return of liquid from said lift to said receptacle, means for supplying air under pressure to said pressure operated deviceY While said' supply and liquid valves are closed, means4 for exhausting air from said receptacle while said liquid valve is open and liquid is flowing from said lift into said receptacle, and means for supplying air toV said compressor while saidV return Valve is closed.

28. In a uid? operatedlifting mechanism, a hydraulic lift, a liquid receptacle having an air space above the liquid therein, a liquid conduit connecting said receptacle with said lift, a valve to control the oW of liquid through said liquid conduit, aconduit to supply air under pressure from said compressor tothe air space in said receptacle, a normally closed supply valve in said supply conduit, an exhaust conduit connected withv said supply conduit between saidV supply valve and said receptacle, a normally closedvalve in said' exhaust conduit, means for separately opening said supply and' exhaust' valves, a return conduit leading. from the air space in said receptacle to the intake off said compressor, a return valve in said. return conduit arranged to be held closed by air pressure when said supply valve is open, means for opening said return valve while said supplyV and exhaust valves are closed to: permit air under pressure to flow from said receptacle: to said compressor, and means for supplying air to saidl compressor' While said returnvalve is closed.

ION V. K. HOTT. 

